The unauthorized taking of merchandise has long been a problem for retail stores. Various efforts have been made to prevent such unauthorized taking, commonly referred to as "shoplifting". Picard devised an electronic article surveillance system of the electro-magnetic type as disclosed in French patent application no. 763,681 published in 1934. The Picard system included a transmitter, a receiver and a ferromagnetic marker. The transmitter would create an electromagnetic field in an interrogation zone, normally between two gates each containing a transmitter and a receiver, and the ferromagnetic marker would have the characteristic of reacting to the electromagnetic field to transmit a signal. This signal would be received by the receivers of the gates and thus detection would be achieved. Many attempts have been made to fabricate ferromagnetic markers that can be readily detected without the need of generating strong fields. In U.S. Pat. No. 4,568,921 issued to Pokalski, Feb. 4, 1987, a marker is disclosed wherein a ferromagnetic wire is incorporated in a marker. U.S. Pat. No. 32,427 to Gregor, May 26, 1987, discloses a large number of a ferromagnetic materials that can be used in a marker. The use of ferromagnetic fibers having a small cross section is disclosed in U.S. Patent application Ser. No. 290,547, assigned to the assignee of the instant patent application. In patent application Ser. No. 290,547, the advantages of the use of a ferromagnetic fiber is disclosed as well as a method of making such fiber through rapid solidification techniques.
In patent application Ser. No. 290,547, supra, a melt of ferromagnetic material was contained in a crucible and a spinning wheel contacted molten ferromagnetic metal received in the crucible to form fibers. Although this system worked well, there were certain disadvantages. A problem arose in trying to achieve continuous fabrication of the ferromagnetic fibers. There are many methods disclosed for producing metallic fibers having a small cross section, see for example U.S. Pat. No. 3,812,901 issued May 28, 1974 to Stewart et al, which are quite similar to the technique described in U.S. patent application Ser. No. 290,547. Other investigators have attempted to fabricate such fibers by using a solid rod of metal that is contacted by a spinning wheel located below and at the lower end of the rod. See for example U.S. Pat. No. 4,523,626 issued to Masumoto et al June 18, 1985. This technique is referred to as a "pendant drop" melt wherein the metal at the tip of the rod is melted either by an electron beam or by an external flame. The pendant drop is accessed at the lower end thereof by a spinning wheel, and surface tension stabilizes the drop against gravity. Unfortunately, this type of method for producing metallic fibers has a number of drawbacks. In the electron beam melting, a high vacuum, between 1.times.10.sup.-6 to 2.times.10.sup.-6 torr is required. In the flame melting technique, severe oxidation can result. Alternate sources of "clean" heat which do not require a vacuum, such as radio frequency heating, are difficult to use in the pendant drop configuration because the additional forces resulting from the electromagnetic waves destabilize the drop. It should also be noted that these previous techniques did not succeed in forming fibers having a diameter of less than about 25.mu..